Why is there a feud between the elves and dwarves?

There was not always animosity between the Elves and the Dwarves. Dwarves made the best armour and the elves often traded and bought and sold. The entrance was the primary access point for their dealings, and was placed their mostly for the purpose of the elves. The elves of Eregion were great craftsmen, and they traded and worked with the dwarves of Moria, and there was great friendship. This ended when Sauron revealed himself, slew the elves' king, Celebrimbor, and the Gates of Moria were shut.